(1) Field of the Invention
The present invention relates to an ozone detecting material for detecting a trace amount of ozone in a gas and a method for detecting ozone.
(2) Description of Related Art
Detecting the presence of a trace amount of ozone in a gas such as air and measuring the ozone concentration are important in view of industrial and environmental problems. In recent years, there has been a growing demand for the development of a material for detecting ozone in a gas such as air and an ozone detection method. This is because although ozone is highly useful as a clean oxidant not leaving any harmful residues when ozone breaks down and recently became more widely used as a bactericide and deodorant for water and air and as a cleaning agent in the semiconductor manufacturing industry, ozone before it breaks down is harmful, even in a trace amount, to the human body.
However, most conventional small-sized low concentration ozone generators used in hospitals, etc. are not equipped with ozone concentration monitors, etc. This is because conventional ozone detectors are large and expensive. Therefore, the development of a small-sized, economically producible ozone detector is desired. Desired is the development of an inexpensive high-sensitive ozone detecting material applicable to the production of such an ozone detector and a simple and easy ozone detection method enabling size reduction of a detector.
Known materials and methods for detecting a trace amount of ozone in a gas such as air include, for example, (1) a detection method utilizing ozone-specific light absorption in the ultraviolet wavelength region, (2) a detection method using the irreversible change in the visible light absorption of a colorant (e.g., indigo dyes) by a reaction with ozone, (3) a detection method using chemiluminescence, and (4) a detection method using the reversible change in the electrical conductivity of indium oxide or the like in a heated state caused by the presence of ozone.
However, these conventional methods have the following problems. In method (1), since very small absorbance changes caused by ozone must be detected, a gas cell with a long optical path length, an expensive high precision photodetector and a light source are required, resulting in a large expensive detector. In method (2), since colorant absorbance change due to ozone is irreversible, the method can be used for one-time only detection of ozone and cannot be used for continuous detection. In method (3), since each measurement requires the step of producing chemiluminescence, the method cannot be used for continuous ozone detection. In method (4), since an ozone detecting material such as indium oxide must be kept heated at a high temperature at all times, the procedure consumes a large amount of energy and a device comprising an ozone detecting material, electrodes, a heater, a voltage applicator, a voltmeter, an ammeter and a stabilization circuit is quite complicated and expensive.
Therefore, it is desired to develop an ozone detecting material and an ozone detection method for a simple-structured, economically producible, small-sized ozone detector. More specifically, desired are an ozone detecting material and an ozone detection method easily provided at low cost and enabling repeated measurement or continuous measurement, the material and method being capable of quickly detecting comparatively high-concentration ozone leakage from a small-sized ozone generator and pipelines by installing a large number of sensors on each ozone generator and each part of the pipelines, even when the ozone concentration is roughly indicated as a concentration region. Also desired are an ozone detecting material and an ozone detection method which can be used for one-time only measurement capable of retaining a record of the ozone detection for a certain period of time.